Extended researches of shallow subsurface structure with using the seismic waveform correlation methods

本课题主要做了以下几方面的研究。首先，对利用地震记录相关函数的各种方法进行了比较。第二，将该方法应用于火山岩地区的地震勘探。第三，在震源变化的地震剖面之间进行了重现性检验。第四，探讨了地下构造动态变化探测的可行性。我们的工作是成功的，第一年和第二年用地震相关方法处理了富士火山和草津-白根火山的地震记录，成功地获得了地震剖面。每项成果都已作为2007年和2008年的论文发表。还尝试了地震相关方法在火山地震中的应用，成功实现了浅层火山构造的S波成像。等效震源记录是由所有震源记录叠加而成的，它可以用来讨论剖面的再现性或入射子波的影响。在火山地震事件上应用地震相关方法是探测火山管道周围动态变化的有效和灵敏的工具。

These following researches have been made in this project. The first, comparison among various methods with using correlation functions of seismograms have been made. The second, the methods have been applied to seismic exploration in volcanic area. The third, reproductivity tests have been made among seismic sections with source variation. The fourth, the feasibility has been discussed for detection of dynamic changes of subsurface structure. Our results on these tasks were successful.Seismograms in Fuji and Kusatsu-Shirane volcanoes have been processed with the seismic correlation methods and seismic sections have been obtained successfully in the first and the second years. Each result has been published as papers on 2007 and 2008. An application to volcanic tremor was also tried to process with the seismic correlation method and S-wave imaging of shallow volcanic structure have been successfully achieved. The equivalent source seismogram which is derived as a stack of all correlerograms has been found as useful to discussing reproductivity of the sections or effect of incident wavelet. Variations in the equivalent source wavelets have been detected and this suggests there may be certain changes among repetitive volcanic tremor.It is concluded that applications of the seismic correlation methods on volcanic seismic events are useful and sensitive tools to detect dynamic changes around volcanic conduits.